1. Field of the Invention
The present invention relates to a lens barrel that includes a plurality of optical elements driven independently of one another along the direction of the optical axis thereof.
2. Description of the Related Art
The lens barrel of a camera that houses the photographic optical system of the camera, known in the related art may include a plurality of movable lens units that move independently of one another along the direction of the optical axis thereof.
At a lens barrel that includes an optical system adopting such a multiple unit structure, lead screws extending parallel to the optical axis and transmission mechanisms that are connected to the movable lens units and each include a threaded portion to engage with the lead screw are disposed so as to drive the movable lens units along the optical axis by rotationally driving the lead screws. One lead screw is disposed in conjunction with each movable lens unit.
Japanese Laid Open Patent Publication No. 2003-241056 discloses a lens barrel that includes two movable lens units. In this lens barrel, two lead screws are disposed adjacent to the optical system, with motors for rotationally driving the individual lead screws disposed side-by-side at the ends of the lead screws on one side.
In the structure described above in which the plurality of lead screws each disposed parallel to the optical axis are driven by motors disposed side-by-side, the distance between the axes of the lead screws is likely to be significant due to the restrictions imposed by the motor size, which makes it difficult to provide a lens barrel as a compact unit, specifically with regard to its measurement along the direction perpendicular to the optical axis of the lens barrel (the direction along which the lead screws are disposed).